Electric discharge device



1935- R. M. SHERRILL ELECTRIC DISCHARGE DEVICE Filed March 26, 1932 mmfl /mw Patented Jan. 15, 1935 UNITED STATES PATENT OFFICE ELECTRIC DISCHARGE DEVICE Richard M. Sherrill, Evanston, Ill., assignor to Central Scientific Company, a corporation of Illinois Application March 26, 1932, Serial No. 601,399

1 Claim. (Cl. 176-42) In scientific laboratories, it is the usual practice be connected to a suitable source of low voltage, to use carbon arc lamps for point sources of inhigh amperage electric current. tense light, and mercury vapor lamps for line The upper portion of the tubular section 11 sources. forms a condensing chamber 1'? over the cathode,

5 As this invention concerns itself only with light and through this chamber, a quantity of mercury, 5 sources that are enclosed within a glass vessel, indicated at 18 and 19,.is introduced. The lamp the carbon arc lamp is not pertinent to this disis then evacuated by means of a suitable vacuum closure, unless housed within a glass tube or its pump, the seal off being indicated at 20. equivalent, but as this is not customary, the To start an are between the two pools of merinvention, for convenience, will be discussed as cury 18 and 19, the lamp is tilted so that an ex- 10 applied to a mercury vapor lamp. cess of mercury will be contained in the leg 11 Because of the intensity of the light emitted of the lamp. When the tube is righted, the excess from a mercury vapor lamp, it is customary to will overflow the elbow 21, and strike an arc provide a housing fitting over the lamp and probetween the two pools of mercury 18 and 19, vided with suitable openings for directing abeam which is thereafter maintained by the ionized 15 of light. This is necessary to protect other mercury vapor. workers in the laboratory from being subjected The restrictions 22 and 23 in the legs 11 and 12 to the intense light rays. of the lamp are for the purpose of preventing the This invention seeks to eliminate the undesirpools of mercury surrounding the electrodes from able glare in an electric discharge device by prouncovering the latter when the tube is tilted to 20 viding means constituting a part of the device strike an are. In this way, the fl w ay itself for limiting the emission of light waves to extend from mercury to m r ry, an the lecpredetermined directions. trodes are thereby protected.

Further and other objects and advantages will Assuming that the mercury vapor lamp is to 25 become apparent as the disclosure proceeds and be used with apparatus requiring a beam of light .25

the description is read in conjunction with the directed to the right (Figs. 1 and 3), this invenaccompanying drawing, in which tion contemplates applying an opaque substance Fig. 1 is a vertical, sectional view taken through to the side and rear portions of the lamp to reatypical mercury vapor lamp to which the present strict emission of light to a forward direction.

invention has been applied: The opaque substance is preferably applied by 30 Fig. 2 is a front view thereof; and fusing it into the glass when the latter is in, a Fig. 3 is a cross sectional view of the tubing olt n s at he paque subs ance may be a y used in the lamp. of the well known materials common in the art While a mercury vapor lamp has been chosen of glass manufacture for rendering glass imperto illustrate an application of the present invenvious to light. 5 tion, it will be understood that the invention is In practice, a small quantity of transparent equally useful in other electric discharge devices lass is cons lidat d with a la r quantity of in which a source of light is enclosed within a opaque glass while thclatteris being a ipu ated on the blow pipe, the result being to form opaque transparent housing, and the claim, therefore, is notto be construed as limited to the specific tublng having a transparent s ction running 40 longitudinally of the tubing.

disclosure herein, except as may be required by express limitations and by the prior art. The tubmg also be made by fu.smg an In the illustrative embodiment of the invention, opaque Substance m transparent glass tubmg. that the mercury vapor lamp generally designated 10 has already been formed, or by any other suitable r comprises a vertical, tubular section or leg 11 ggi of heavy cross hatching and stipling in having a laterally and downwardly extending the drawing is to indicate opaqueness branch 12 terminating at a point 13 below the The advantages of making the from lower extremity 14 The lafnp is ing such as has been described are apparent. pliefelflbly made of h1gh quahty heat reslstant There is no necessity for mounting the lamp in a 50 E1 2 Order Wlthstand the ravage 0f the housing, or otherwise shielding the lamp, when e o no are. such tubing is used; A saving in cost as well Plosiitilifir anili1 nlegaiiive delectiroclizes 1t:1 arid 16 are as! conventience in handling are direct results of sea e oug e c ose en s an respece inven ion. tively of the legs 12 and 11 and. are adapted to The invention is obviously applicable t ll 55 electric discharge devices of the type in which an electric current is conducted through a glass vessel between spaced electrodes for producing a source of light.

What I claim therefore, ls:

In a mercury vapor lamp, a tubular glass envelope, a quantity of mercury in the envelope, spaced electrodes adapted to be connected to a source of potential for producing an electrical discharge in said envelope of intense luminosity, said envelope being made of glass tubing that is opaque except for a longitudinal strip of transparent glass running substantially throughout its length.

RICHARD M. SHERRILL. 

